These findings are in line with earlier research that
found about 80 per cent of 16-17 year olds in 27 U.S. states
who were licensed after completing high school driver education would not have been licensed until they were 18 or
older in the absence of high school driver education.5 Three
pieces of research-the British experiment,4 the 27 state
study, and the research reported here-have now provided
the necessary and sufficient conditions for the conclusion
that driver education in high schools is a major contributing
factor to the early licensure of teenagers to drive and, as a
result of this earlier exposure, their increased involvement
as drivers in serious crashes. Licensure and crashes increase
when driver education is increased; they decline in parallel
when driver education is decreased and the changes occur
specifically in the high school trained group. No evidence to
support a contrary conclusion has been forthcoming.